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A brief history of genetic testing

From science fiction to a multimillion dollar industry: how genetic testing revolutionized medicine and grew into a booming business.

 

1902: Chromosomes are recognized as the carriers of genetic material.

1953: The iconic double helix structure of DNA is discovered.

1977: The very first DNA sequencing technique is developed.

1987: The Human Genome Project launched with the goal to sequence all 3 billion letters of a human genome. It was completed in 2003.

 

Those are some of the main turning points in the history of genetic testing and analyzing. The knowledge gathered in the span of a century is utilized today to determine bloodlines, evaluate the risk for diseases, and even determine your unique dietary and fitness predispositions.

It all began with blood

In the early 1920s, scientists identified 4 blood types, based on the presence or absence of antigens A and B: A, B, AB, and O. The ABO blood typing system made blood transfusions and organ donating significantly safer and more successful. But because blood type is inherited, it also marked the beginning of genetic testing as a tool for determining parental relationships.

A significant leap forward was made in the mid-1970s, when scientists discovered a protein called the Human Leukocyte Antigen (HLA), responsible for the regulation of our immune system. HLAs are highly polymorphic (have many different alleles), which makes them useful for high-accuracy identification, but HLA testing required lots of blood and had to be performed within days of sample collection.

DNA profiling

In 1980s DNA profiling emerged. Also called DNA fingerprinting, it is a way of determining a person’s DNA characteristics, which are as unique as his fingerprints – hence the name. Scientists developed a technique called the Restriction Fragment Length Polymorphism (RFLP), which became the first genetic test using DNA.

It is a technique that exploits polymorphisms – highly variable DNA regions – to distinguish individuals, populations, or species, or to detect the locations of genes within a sequence. This is achieved by using the enzyme restriction endonuclease which fragments (cuts) the DNA whenever it recognizes a short, specific DNA fragment.

In the early nineties, RFLP was replaced by Polymerase Chain Reaction (PCR), which enables scientists to make copies of a specific DNA sequence. PCR imitates natural DNA replication but limits it to specific DNA sequences which we are interested in. Just like a DNA copying machine!

Because it requires a very small sample of DNA, it is widely used in forensics, where scientists often have only trace amounts of genetic material available. PCR also has the broad medical and diagnostic application: determining gene expression, tissue typing before organ transplantation, early diagnosis of certain cancers, identifying infectious diseases, etc.

SNPs

New century brought the discovery of the SNP (Single Nucleotide Polymorphism). SNPs (pronounced “snips”) are the most common type of genetic variation in humans.

SNPs are substitutions of a single nucleotide (DNA building block) at a specific location in the genome. For example: in most individuals in the population a particular location in the human genome – let’s call it position X – is occupied by a certain nucleotide, let’s say A (adenine). However, in some, the position X is taken by nucleotide C (cytosine). This means that there is a snip at the position X. The two possible nucleotide variations – in this case, A or C – are called alleles for this position. If you need to refresh your knowledge of nucleotides and alleles, head to our blog posts about the basics of genetics!

So how often do SNPs occur? In a typical human genome, there can be SNPs at up to 5 million sites! This abundance makes them ideal genetic markers for scientists to locate genes associated with diseases. The majority of SNPs actually do not affect our health, but those that do can provide essential health-related information like predicting response to drugs, susceptibility to toxins or risk of developing particular diseases.

Scientists are currently searching for SNPs which are associated with complex diseases such as heart disease, diabetes, and cancer.

Next Generation Sequencing

DNA sequencing means determining the sequence of nucleotides in the DNA, or to put it simply, the order of the four bases of DNA: A, C, T, and G. The first DNA sequence was created in the early 1970s, and since then the method has become indispensable in medical diagnostics, forensic biology, and other fields.

NGS (Next Generation Sequencing) is the newest technique for genetic analysis. By utilizing parallel analysis (sequencing at thousands of overlapping locations in the DNA) and bioinformatics (computer programs capable of analyzing massive amounts of data), NGS techniques greatly increased speed and reduced costs and manpower needed for the sequencing.

WGS (Whole Genome Sequencing) is a process of analyzing the entire genome of an individual person. This means identifying all 3 billion nucleotides! Such a vast quantity of data has huge potential, especially in terms of developing a personalized medical treatment. Imagine how much more effectively we could be treating patients if doctors knew exactly how their bodies will respond to the dosage they are about to receive? By analyzing genes responsible for drug metabolism, such a tailored approach is indeed possible – thanks to WGS.

Being able to sequence the entire human genome in a single day instead of in decades, it is not hard to imagine how thoroughly the newest gene analyzing techniques have revolutionized the field!

How do I benefit from the advances in genetic testing?

In recent years DNA testing has left the confines of forensic laboratories and hospitals to become a valuable tool for improving people’s health and wellbeing.

If you ask 1,000 people for advice on staying healthy, you will receive 1,000 different answers. And none of them take into account your unique biology. The only way to really help your body become its best version is to know it intimately. What benefits it and what does it harm?

So for you personally, this is what all those decades of genetic research have culminated to – with the help of genetic analysis, specifically SNPs, a simple cheek swab translates into ready-to-use knowledge about your genetic predispositions!

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